I've heard Dave H. say on more than one interview that the FBI told them early on that Natalee was dead. I wonder if that was based on the "Deepak killed her" statement from Joran?
I believe it came from a partial confession that Joran made.
Something bad happened, I buried her in the sand and I will take you to where I buried her - statement on June 11th.
Then later he changed it to Deepak raped and killed her, then buried her - statement on the 13th of June.